1. Field of the Invention:
This invention relates to the art of fireplace inserts and, particularly, to double wall fireplace inserts that have convection air channels between the firebox and an outer shell to improve the thermal efficiency of the fireplace so that the insert serves as a heat exchanger between the hot walls of the inner firebox and the circulating air.
2. Description of the Prior Art: A careful search of the prior art has been made, and several patents were found to be of interest.
U.S. Pat. No. 4, 351,315 to Babbage apparently was developed in England, and it covers a solid fuel boiler that apparently is burning fossil fuel such as coal rather than firewood, as the present invention. This solid fuel boiler is mounted in the wall divider that may be an exterior wall of the building, or it may divide two interior rooms. This solid fuel boiler has a flue hopper. Also, there is a cooling water jacket around the flue ways so that water must be furnished with this solid fuel boiler, and that's not true in the present invention which uses convection air currents for transferring the heat back to the room to be heated.
The next patent is U.S. Pat. No. 4,576,141 to Lillard. It describes a fireplace apparatus where there is an ash drawer which is removable without opening the fireplace door. This ash drawer is very small, and there is not enough space to load firewood through the drawer opening in which the ash drawer sits. The firebox is mounted on four vertical legs. Each leg has a wheel on the bottom making the firebox movable. This is not a very desirable design, and it would not compete with the present invention.